An information distribution system that selects distribution information based on activity information representing an activity of a user and transmits the selected distribution information to a user terminal of the user is known (e.g., refer to Patent Document 1). Activity information is, for example, location information representing the location of a user terminal, purchasing information representing a product that a user has purchased, or the like.
A server device included by this information distribution system has a registrant file for registering users possessing user terminals, a purchasing history file in which purchasing histories are collected, a location information file (an activity pattern file) in which activities of registrants are collected by using GPS (Global Positioning System), and an advertisement request file including distribution information representing advertisement. This server device extracts a registrant of a target for transmission of distribution information representing advertisement based on the purchasing history file, the activity pattern file, and the advertisement request file.
According to this information distribution system, it is possible to transmit properly selected distribution information (i.e., offer “personalized service”) to a user terminal based on the purchasing history of a user and the activity of the user.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-256713
In the information distribution system described above, the server device is configured to store the registrant file, the purchasing history file and the activity pattern file in association with each other. That is to say, the server device stores information enabling specification of an individual as a user (e.g., private information such as a name and a telephone number) and activity information representing an activity of a user in association with each other. Therefore, there is a problem that an activity of a specific user may be known by a third party in a case that information is leaked from the server device.